drivers/dma-buf/dma-buf.c | 63 +++++++++++++++++++++++++++------
include/linux/dma-buf.h | 11 ++++++
include/uapi/linux/dma-buf.h | 68 ++++++++++++++++++++++++++++++++++++
3 files changed, 132 insertions(+), 10 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 32f55640890c..262c4706f721 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -125,6 +125,32 @@ static struct file_system_type dma_buf_fs_type = {
.kill_sb = kill_anon_super,
};
+static int __dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
+{
+ int ret;
+
+ /* check if buffer supports mmap */
+ if (!dmabuf->ops->mmap)
+ return -EINVAL;
+
+ ret = dmabuf->ops->mmap(dmabuf, vma);
+
+ /*
+ * If the exporter claims to support coherent access, ensure the
+ * pgprot flags match the claim.
+ */
+ if ((dmabuf->map_info != DMA_BUF_MAP_INCOHERENT) && !ret) {
+ pgprot_t wc_prot = pgprot_writecombine(vma->vm_page_prot);
+ if (dmabuf->map_info == DMA_BUF_COHERENT_WC) {
+ WARN_ON_ONCE(pgprot_val(vma->vm_page_prot) != pgprot_val(wc_prot));
+ } else {
+ WARN_ON_ONCE(pgprot_val(vma->vm_page_prot) == pgprot_val(wc_prot));
+ }
+ }
+
+ return ret;
+}
+
static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
{
struct dma_buf *dmabuf;
@@ -134,16 +160,12 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
dmabuf = file->private_data;
- /* check if buffer supports mmap */
- if (!dmabuf->ops->mmap)
- return -EINVAL;
-
/* check for overflowing the buffer's size */
if (vma->vm_pgoff + vma_pages(vma) >
dmabuf->size >> PAGE_SHIFT)
return -EINVAL;
- return dmabuf->ops->mmap(dmabuf, vma);
+ return __dma_buf_mmap(dmabuf, vma);
}
static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
@@ -326,6 +348,27 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
return 0;
}
+static long dma_buf_info(struct dma_buf *dmabuf, void __user *uarg)
+{
+ struct dma_buf_info arg;
+
+ if (copy_from_user(&arg, uarg, sizeof(arg)))
+ return -EFAULT;
+
+ switch (arg.param) {
+ case DMA_BUF_INFO_MAP_INFO:
+ arg.value = dmabuf->map_info;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (copy_to_user(uarg, &arg, sizeof(arg)))
+ return -EFAULT;
+
+ return 0;
+}
+
static long dma_buf_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
@@ -369,6 +412,9 @@ static long dma_buf_ioctl(struct file *file,
case DMA_BUF_SET_NAME_B:
return dma_buf_set_name(dmabuf, (const char __user *)arg);
+ case DMA_BUF_IOCTL_INFO:
+ return dma_buf_info(dmabuf, (void __user *)arg);
+
default:
return -ENOTTY;
}
@@ -530,6 +576,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
dmabuf->priv = exp_info->priv;
dmabuf->ops = exp_info->ops;
dmabuf->size = exp_info->size;
+ dmabuf->map_info = exp_info->map_info;
dmabuf->exp_name = exp_info->exp_name;
dmabuf->owner = exp_info->owner;
spin_lock_init(&dmabuf->name_lock);
@@ -1245,10 +1292,6 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
if (WARN_ON(!dmabuf || !vma))
return -EINVAL;
- /* check if buffer supports mmap */
- if (!dmabuf->ops->mmap)
- return -EINVAL;
-
/* check for offset overflow */
if (pgoff + vma_pages(vma) < pgoff)
return -EOVERFLOW;
@@ -1262,7 +1305,7 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
vma_set_file(vma, dmabuf->file);
vma->vm_pgoff = pgoff;
- return dmabuf->ops->mmap(dmabuf, vma);
+ return __dma_buf_mmap(dmabuf, vma);
}
EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 71731796c8c3..37923c8d5c24 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -23,6 +23,8 @@
#include <linux/dma-fence.h>
#include <linux/wait.h>
+#include <uapi/linux/dma-buf.h>
+
struct device;
struct dma_buf;
struct dma_buf_attachment;
@@ -307,6 +309,13 @@ struct dma_buf {
*/
size_t size;
+ /**
+ * @map_info:
+ *
+ * CPU mapping/coherency information for the buffer.
+ */
+ enum dma_buf_map_info map_info;
+
/**
* @file:
*
@@ -533,6 +542,7 @@ struct dma_buf_attachment {
* @ops: Attach allocator-defined dma buf ops to the new buffer
* @size: Size of the buffer - invariant over the lifetime of the buffer
* @flags: mode flags for the file
+ * @map_info: CPU mapping/coherency information for the buffer
* @resv: reservation-object, NULL to allocate default one
* @priv: Attach private data of allocator to this buffer
*
@@ -545,6 +555,7 @@ struct dma_buf_export_info {
const struct dma_buf_ops *ops;
size_t size;
int flags;
+ enum dma_buf_map_info map_info;
struct dma_resv *resv;
void *priv;
};
diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
index b1523cb8ab30..07b403ffdb43 100644
--- a/include/uapi/linux/dma-buf.h
+++ b/include/uapi/linux/dma-buf.h
@@ -85,6 +85,72 @@ struct dma_buf_sync {
#define DMA_BUF_NAME_LEN 32
+/**
+ * enum dma_buf_map_info - CPU mapping info
+ *
+ * This enum describes coherency of a userspace mapping of the dmabuf.
+ *
+ * Importing devices should check dma_buf::map_info flag and reject an
+ * import if unsupported. For example, if the exporting device uses
+ * @DMA_BUF_COHERENT_CACHED but the importing device does not support
+ * CPU cache coherency, the dma-buf import should fail.
+ */
+enum dma_buf_map_info {
+ /**
+ * @DMA_BUF_MAP_INCOHERENT: CPU mapping is incoherent.
+ *
+ * Use of DMA_BUF_IOCTL_SYNC is required for CPU managed coherenency.
+ */
+ DMA_BUF_MAP_INCOHERENT,
+
+ /**
+ * @DMA_BUF_COHERENT_WC: CPU mapping is coherent but not cached.
+ *
+ * A cpu mmap'ing is coherent, and DMA_BUF_IOCTL_SYNC is not required.
+ * However fences may be still required for synchronizing access. Ie.
+ * coherency can only be relied upon by an explicit-fencing userspace.
+ * An implicit-sync userspace must still use DMA_BUF_IOCTL_SYNC.
+ *
+ * The cpu mapping is writecombine.
+ */
+ DMA_BUF_COHERENT_WC,
+
+ /**
+ * @DMA_BUF_COHERENT_CACHED: CPU mapping is coherent and CPU cached.
+ *
+ * A cpu mmap'ing is coherent, and DMA_BUF_IOCTL_SYNC is not required.
+ * However fences may be still required for synchronizing access. Ie.
+ * coherency can only be relied upon by an explicit-fencing userspace.
+ * An implicit-sync userspace must still use DMA_BUF_IOCTL_SYNC.
+ *
+ * The cpu mapping is cached.
+ */
+ DMA_BUF_COHERENT_CACHED,
+};
+
+/**
+ * struct dma_buf_info - Query info about the buffer.
+ */
+struct dma_buf_info {
+
+#define DMA_BUF_INFO_MAP_INFO 1
+
+ /**
+ * @param: Which param to query
+ *
+ * DMA_BUF_INFO_MAP_INFO:
+ * Returns enum dma_buf_map_info, describing the coherency and
+ * caching of a CPU mapping of the buffer.
+ */
+ __u32 param;
+ __u32 pad;
+
+ /**
+ * @value: Return value of the query.
+ */
+ __u64 value;
+};
+
#define DMA_BUF_BASE 'b'
#define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
@@ -95,4 +161,6 @@ struct dma_buf_sync {
#define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, __u32)
#define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, __u64)
+#define DMA_BUF_IOCTL_INFO _IOWR(DMA_BUF_BASE, 2, struct dma_buf_info)
+
#endif
